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7 Pin Wiring - Yellow Wire???

Throttlemonkey
Explorer
Explorer
2006 Outback 23 KRS

I am replacing the 7 Pin Pigtail, it was worn out and unreliable. Interesting thing, when I was disconnecting the old one the yellow wire was clipped off and unused. I did not connect the yellow one on the new pigtail and the left blinker/brake still works! Every schematic I have seen show the yellow as left blinker... On the trailer end there is only a yellow/white wire, no pure yellow, and that goes to the upper marker lights.

Usually I am trying to figure out why things don't work that should, now I am trying to figure out why this is working when it shouldn't be!

What am I missing?
10 REPLIES 10

Miles_Away
Explorer
Explorer
If it was on the truck side, clipped off and not used and everything else worked, it might be for a back-up light. Most truck plugs are wired for them, but most trailer don't have back-up lights.
M & M :C On the road again!
2007 GMC 3500-SRW-Duramax-longbed-4X4
2008 Keystone EVEREST 348R 5th wheel
2002 SUNDOWNER gooseneck horse trailer

LanceRKeys
Explorer
Explorer
Just went through this with my truck. I ended up going wire by wire with a test light to see what each one did and wired it accordingly. Mine may or may not be to the standard, but it works correctly.

Oh, on another note, wear safety glasses when drilling for a mounting location for the plug. A simple job turned into an emergency room visit to get metal pulled out of my eye.

mkirsch
Nomad II
Nomad II
I must've purchased an RV plug for a utility application, or vice versa, at some point because I followed the colors molded into the plug when wiring it, but they were wrong.

Putting 10-ply tires on half ton trucks since aught-four.

JBarca
Nomad II
Nomad II
Yes, as DougE stated there are different wiring color standards depending on who puts them on.

See here from Etrialer some nice pic's showing this





They sell both configurations just you need to realize there is a difference and pick the right one when buying.

The good news, the auto makers at least have the pins all in the right place so if the colors change, it does not affect the trailer working.
2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10 RA, 21,000 GCWR, 11,000 GVWR, upgraded 2 1/2" Towbeast Receiver. Hitched with a 1,700# Reese HP WD, HP Dual Cam to a 2004 Sunline Solaris T310R travel trailer.

Throttlemonkey
Explorer
Explorer
Great info, I had never seen that before, much appreciated!

The yellow wire is likely for backup lights which is perfect, I just bought some LED floods to mount on the side of the trailer for backing up my driveway at night, now I know where to connect them!

DougE
Explorer
Explorer
There are 2 primary standards. The SAE standard is used on cargo trailers and is what most of us know. There is an RV standard that some of the RV manufacturers use that sounds like what you are observing. One reference for this is: http://www.hopkinstowingsolutions.com/doc/trailer-wiring-codes.pdf
I personally wire all my trailers to the SAE standard as being the most universally used and recognized.
Currently Between RVs

enblethen
Nomad
Nomad
Look closely as it could be faded or weak orange which is normally connected to the center pin. This center pin is an auxiliary connection for items like back up lights.

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker

Throttlemonkey
Explorer
Explorer
downtheroad wrote:
L turn and stop light.


Got that, read post, yellow wire not connected to anything but L signal works???

sch911
Explorer
Explorer
Don't count on the wiring colors to match on either side of the connection. Go by which pin # does what.
OEM Auto Engineer- Embedded Software Team
09 Holiday Rambler Endeavor 41SKQ Cummins ISL
2012 Jeep Grand Cherokee Limited Toad

downtheroad
Explorer
Explorer
L turn and stop light.
"If we couldn't laugh we would all go insane."

Arctic Fox 25Y
GMC Duramax
Blue Ox SwayPro